1. Field of the Invention
This present invention is directed to blowout preventers, to tubular-shearing blades for them, and methods of their use.
2. Description of Related Art
The prior art discloses a wide variety of blowout preventers and tubular-shearing blades for blowout preventer bonnets.
Typical blowout preventers have selectively actuatable rams bonnets secured to the body which are either pipe rams (to contact, engage, and encompass pipe and/or tools to seal a wellbore) or shear rams (to contact and physically shear a tubular, casing, pipe or tool used in wellbore operations). Rams typically upon activation and subsequent shearing of a tubular, seal against each other over a center of a wellbore.
Blowout preventers and tubular-shearing blades for them are disclosed in many U.S. patents, including, but not limited to, U.S. Pat. Nos. 3,946,806; 4,043,389; 4,313,496; 4,132,267, 4,558,842; 4,969,390; 4,492,359; 4,504,037; 2,752,119; 3,272,222; 3,744,749; 4,253,638; 4,523,639; 5,025,708; 5,056,418; 5,400,857; 5,575,452; 5,655,745; and 5,918,851; 4,313,496; 4,550,895; 5,360,061; 4,923,005; 4,537,250; 5,515,916; 6,173,770; 3,863,667; 6,158,505; 5,575,451; 4,057,887; 5,505,426; 3,955,622; 3,554,278; and 5,013,005.
There has long been a need, recognized by the present inventor for a blowout preventer which can effectively and efficiently shear tubulars, e.g. tubulars used in wellbore operations, including relatively large tubulars such as casing, drill collars, and drill pipe tool joints. In certain prior tubular shearing systems, a tool joint is located so that shearing rams do not encounter the tool joint, but shear only a relatively smaller portion of the tubular. Proper location takes time and, if a tool joint is improperly located, no or ineffectual shearing may result.